Who will win depends on various factors.
For the Colts to win:
1) Defense must harass Rex Grossman and make he sure he plays like he did in the middle of the season--turnover prone.
2) Peyton Manning must utilize every weapon he has to keep the Bears defense off balance. Notice how he beat the Patriots--mix of runs and short passes, spreading out their defense. He must do the same to the Bears for the Colts to win.
3) Joseph Addai must have a decent game. He does not have to go over 100 yards, but needs 20-25 carries for around 90 yards to wear down the Bears D, so Manning will get opportunites for the big play.
For the Bears to win:
1) Stop the big play--take away the big play and you have taken Manning down to human levels.
2) Grossman must not turn the ball over. The more times you give Manning the ball, the more times he will score. The Bears offense cannot keep up with Manning, so Grossman cannot give Manning more opportunites with the ball.
3) Run the ball, and run it well. The Bears have two physical backs, and they need to run the ball early and often to wear down the quick Indy defense. Get the Colts D tired, and then you will find opportunities to hit Bernard Berriman or Musin Muhammad for a big play.
Who I think will win:
I say that the Colts will win. They finally got the monkey off their backs by beating New England. For the Bears, they never know what form Rex Grossman will be in--his dominating early season form or his horrendous, turnover-crazy form from the middle of the year. The Colts defense has stepped it up in the playoffs, and that may be enough to give Manning his first Super Bowl title.
Colts 31, Bears 17